Examples of biocompatible materials that have been proposed for use in augmenting soft tissue in the practice of plastic and reconstructive surgery, include collagen, gelatin beads, beads of natural or synthetic polymers such as polytetrafluoroethylene, silicone rubber and various hydrogel polymers, such as polyacrylonitrile-polyacrylamide hydrogels.
Most often, the biomaterials are delivered to the tissue site where augmentation is desired by means of an injectable composition which comprises the biomaterial and a biocompatible fluid that acts as a lubricant to improve the injectability of the biomaterial suspension. The injectable biomaterial compositions can be introduced into the tissue site by injection from a syringe intradermally or subcutaneously into humans or other mammals to augment soft tissue, to correct congenital anomalies, acquired defects or cosmetic defects. They may also be injected into internal tissues such as tissue defining sphincters to augment such tissue in the treatment of incontinence, and for the treatment of unilateral vocal cord paralysis.
U.K Patent Application No. 2,227,176 to Ersek et al, relates to a microimplantation method for filling depressed scars, unsymmetrical orbital floors and superficial bone defects in reconstructive surgery procedures using microparticles of about 20 to 3,000 microns which may be injected with an appropriate physiologic vehicle and hypodermic needle and syringe in a predetermined locus such as the base of depressed scars, beneath skin areas of depression and beneath perichondrium or periosteum in surface irregularities of bone and cartilage. Textured microparticles can be used, including silicone, polytetrafluoroethylene, ceramics or other inert substances. In those instances wherein the requirement is for hard substances, biocompatible material such as calcium salts including hydroxyapatite or crystalline materials, biocompatible ceramics, biocompatible metals such as stainless steel particles or glass may be utilized. Appropriate physiological vehicles have been suggested, including saline, various starches, polysaccharides, and organic oils or fluids.
U.S. Pat. No. 4,803,075 to Wallace et al, relates to an injectable implant composition for soft tissue augmentation comprising an aqueous suspension of a particulate biocompatible natural or synthetic polymer and a lubricant to improve the injectability of the biomaterial suspension.
U.S. Pat. No. 4,837,285 to Berg et al, elates to a collagen-based composition for augmenting soft tissue repair, wherein the collagen s in the form of resorbable matrix beads having an average pore size of about 50 to 350 microns, with the collagen comprising up to about 10% by volume of the beads.
U.S. Pat. No. 4,280,954 to Yannas et al, relates to a collagen-based composition for surgical use formed by contacting collagen with a mucopolysaccharide under conditions at which they form a reaction product and subsequently covalently crosslinking the reaction product.
U.S. Pat. No. 4,352,883 to Lim discloses a method for encapsulating a core material, in the form of living tissue or individual cells, by forming a capsule of polysaccharide gums which can be gelled to form a shape retaining mass by being exposed to a change in conditions such as a pH change or by being exposed to multivalent cations such as calcium.
Namiki, "Application of Teflon Paste for Urinary Incontinence-Report of Two Cases", Urol. Int., Vol. 39, pp. 280-282, (1984), discloses the use of a polytetrafluoroethylene paste injection in the subdermal area to treat urinary incontinence.
Drobeck et al, "Histologic Observation of Soft Tissue Responses to Implanted, Multifaceted Particles and Discs of Hydroxylapatite", Journal of Oral Maxillofacial Surgery, Vol. 42, pp. 143-149, (1984), discloses that the effects on soft tissue of long and short term implants of ceramic hydroxylapatite implanted subcutaneously in rats and subcutaneously and subperiosteally in dogs. The inventions consisted of implanting hydroxylapatite in various sizes and shapes for time periods ranging from seven days to six years to determine whether migration and/or inflammation occurred.
Misiek et al., "Soft Tissue Responses to Hydroxylapatite Particles of Different Shapes", Journal of oral Maxillofacial Surgery, Vol. 42, pp. 150-160, (1984), discloses that the implantation of hydroxylapatite in the form of sharp edged particles or rounded particles in the buccal soft tissue pouches produced inflammatory response at the implant sites with both particle shapes. Each of the particles weighed 0.5 grams. However, inflammation resolved at a faster rate at the sites implanted with the rounded hydroxylapatite particles.
Shimizu, "Subcutaneous Tissue Responses in Rats to Injection of Fine Particles of Synthetic Hydroxyapatite Ceramic", Biomedical Research, Vol. 9, No. 2, pp. 95-111 (1988), discloses that subcutaneous injections of fine particles of hydroxyapatite ranging in diameter from about 0.65 to a few microns and scattered in the tissue were phagocytized by macrophages in extremely early stages. In contrast, larger particles measuring several microns in diameter were not phagocytized, but were surrounded by numerous macrophages and multinucleated giant cells. It was also observed that the small tissue responses to hydroxyapatite particles were essentially a non-specific foreign body reaction without any cell or tissue damage.
R. A. Appell, "The Artificial urinary Sphincter and Periurethral Injections", Obstetrics and Gynecology Report. Vol. 2, No. 3, pp. 334-342, (1990), is a survey article disclosing various means of treating urethral sphincteric incompetence, including the use of injectables such as polytetrafluoroethylene micropolymer particles of about 4 to 100 microns in size in irregular shapes, with glycerin and polysorbate. Another periurethral injectable means consists of highly purified bovine dermal collagen that is crosslinked with glutaraldehyde and dispersed in phosphate-buffered physiologic saline.
Politano et al., "Periurethral Teflon Injection for Urinary Incontinence", The Journal of Urology, Vol. 111, pp. 180-183 (1974), discloses the use of polytetrafluoroethylene paste injected into the urethra and the periurethral tissues to add bulk to these tissues to restore urinary control in both female and male patients having urinary incontinence.
Malizia et al, "Migration and Granulomatous Reaction After Periurethral Injection of Polytef (Teflon)", Journal of the American Medical Association, Vol. 251, No. 24, pp. 3277-3281, Jun. 22-29 (1984), discloses that although patients with urinary incontinence have been treated successfully by periurethral injection of polytetrafluoroethylene paste, a study in continent animals demonstrates migration of the polytetrafluoroethylene particles from the inspection site.
Claes et al, "Pulmonary Migration Following Periurethral Polytetrafluoroethylene Injection for Urinary Incontinence", The Journal of Urology, Vol. 142, pp. 821-2, (September 1989), confirms the finding of Malizia in reporting a case of clinically significant migration of polytetrafluoroethylene paste particles to the lungs after periurethral injection.
Ersek et al, "Bioplastique: A New Textured Copolymer Microparticle Promises Permanence in Soft-Tissue Augmentation", Plastic and Reconstructive Surgery, Vol. 87, No. 4, pp. 693-702, (April 1991), discloses the use of a biphasic copolymer made of fully polymerized and vulcanized methylmethylpoly-siloxane mixed with a plasdore hydrogel, and used in reconstructing cleft lips, depressed scars of chicken pox and indentations resulting from liposuction, glabella frown wrinkles and soft tissue augmentation of thin lips. The biphasic copolymer particles were found to neither migrate nor become absorbed by the body were textured and had particle sizes varying from 100 to 600 microns.
Lemperle et al. "PMMA Microspheres for Intradermal Implantation: Part I. Animal Research", Annals of Plastic Surgery, Vol. 26, No. 1, pp. 57-63, (1991), discloses the use of polymethylmethacrylate microspheres having particle sizes of 10 to 63 microns in diameter used for correction of small deficiencies within the dermal corium to treat wrinkles and acne scars.
Kresa et al, "Hydron Gel Implants in Vocal Cords", Otolaryngology Head and Neck Surgery, Vol. 98. No. 3, pp. 242-245, (March 1988), discloses a method for treating vocal cord adjustment where there is insufficient closure of the glottis which comprises introducing a shaped implant of a hydrophilic gel that has been previously dried to a glassy, hard state, into the vocal cord.
Hirano et al, "Transcutaneous Intrafold Injection for Unilateral Vocal Cord Paralysis: Functional Results", Ann Otol. Rhinol. Laryngol., Vol. 99, pp. 598-604 (1990), discloses the technique of transcutaneous intrafold silicone injection in treating glottic incompetence caused by unilateral vocal fold paralysis. The silicone injection is given under a local anesthetic with the patient in a supine position, wherein the needle is inserted through the cricothyroid space.
Hill et al, "Autologous Fat Injection for Vocal Cord Medialization in the Canine Larynx", Laryngoscope, Vol. 101, pp. 344-348 (April 1991), discloses the use of autologous fat as an alternative to Teflon.RTM. collagen as the implantable material in vocal cord medialization, with a view to its use as an alternative to non-autologous injectable material in vocal cord augmentation.
Mikaelian et al, "Lipoinjection for Unilateral Vocal Cord Paralysis", Laryngoscope, Vol. 101, pp. 4654-68 (May 1991), discloses that the commonly used procedure of injecting Teflon.RTM. paste to improve the caliber of voice in unilateral vocal cord paralysis has a number of drawbacks, including respiratory obstruction from overinjected Teflon.RTM. and unsatisfactory voice quality. In this procedure, lipoinjection of fat commonly obtained from the abdominal wall appears to impart a soft bulkiness to the injected cord while allowing it to retain its vibratory qualities. The injected fat is an autologous material which can be retrieved if excessively overinjected.
Strasnick et al, "Transcutaneous Teflon.RTM. Injection for Unilateral Vocal Cord Paralysis: An Update", Laryngoscope, Vol. 101, pp. 785-787 (July 1991), discloses the procedure of Teflon.RTM. injection to restore glottic competence in cases of paralytic dysphonia.